GeoLog

The absorption of atmospheric CO₂ by the oceans results in a decline in ocean pH, hence ‘ocean acidification’, and reduces carbonate ion availability. This presents a problem to calcifying organisms (those that deposit calcium as either calcite or aragonite as hard parts) because they cannot produce their shells, valves (in the case of bivalves), or tests (in the case of diatoms) as readily.

To explain this, we need a little chemistry. When CO₂ dissolves, it combines with water to form carbonic acid (H₂CO₃). This then breaks down to form bicarbonate (HCO₃^-) when one hydrogen ion is lost, and then carbonate (CO₃^2-) as the other hydrogen ion is lost. This carbonate is the important stuff, as it combines with calcium to form the calcium carbonate (CaCO₃) used by bivalves to produce shells. If something (such as the ocean) is more acidic, there must be more hydrogen ions available. These hydrogen ions interfere with the calcification process as they bond with carbonate, meaning there is less available for shell formation.

Calcification: carbonate chemistry in action!

This process is relatively well established for a number of calcifying organisms, although there are exceptions to (the coccolith, Emiliania huxleyi, for example) and the response to elevated CO₂ levels is not uniform across species.

Much of current research has focussed on the effect of constant CO₂ levels on calcification, but what about animals that live in environments where the CO₂ concentration is constantly changing? The availability of carbonate in estuaries is particularly variable as CO₂ concentrations vary seasonally (there’s a greater carbon load in the winter as storms wash nutrients into rivers), diurnally and with the tide. The impact of elevated CO₂ levels on an organism is also dependant on its life stage; something that is particularly true of bivalves.

Bivalve larvae. Photo credit: Minami Himemiya (source).

Bivalves spend the first part of their life in the plankton, first as a veliger (a relatively amorphous looking ciliated blob) and then as a pediveliger (that same blob, but this time with an identifiable foot) before metamorphosing into a miniature adult. During these larval stages, they are particularly vulnerable to ocean acidification and, until recently, both the reasons behind this, and the longer-term implications of this vulnerability, were unclear.

This is where doctors Christopher Gobler and Stephanie Talmage come in. They took to the lab to tackle why larvae are especially vulnerable to acidification and what this means for them in both the short and long term. It’s impossible to take a look at how all bivalves respond to acidification, though, so to tackle these questions, two bivalve species, the hard-shelled clam (Mercenaria mercenaria) and the Atlantic bay scallop (Argopecten irradians) joined the team.

The Atlantic bay scallop, Argopecten irradians. Photo credit: Rachael Norris and Marina Freudzon (source).

Using their RNA:DNA ratio as a proxy for growth and the uptake of a radioactive calcium isotope, ⁴⁵Ca, to estimate calcification, Gobler and Talmage found that growth in the presence of elevated CO₂ results in individuals of a smaller size. This is because there is less calcium available for uptake. Their findings, revealed that high CO₂ concentrations, not only affected size, but also negatively impacted bivalve physiology, as individuals reared in these conditions were found to have thinner shells. Shells are an important defence against predators and the reduction in shell thickness (and hence strength) may put them at greater risk from predation.

The higher the CO2, the slower the calcium uptake: calcium uptake rates of larval Atlantic bay scallop, Argopecten irradians, under different CO2 concentrations over a 12-hour period (Gobler and Talmage, 2013).

When transferred from a high CO₂ environment to an environment with an ambient CO₂ concentration, larvae grew faster than those in ambient conditions throughout the whole of their development. However, this higher growth rate doesn’t compensate for the low calcification rate during larval stages, as their final is still smaller than individuals reared in ambient conditions at all life stages. This “legacy effect” presents a significant problem for adult bivalves, due to the detrimental impact of reduced calcification on their defences.

By Sara Mynott, EGU Communications Officer

Reference:

Gobler, C. J. and Talmage, S. C.: Short- and long-term consequences of larval stage exposure to constantly and ephemerally elevated carbon dioxide for marine bivalve populations, Biogeosciences, 10, 2241-2253, doi:10.5194/bg-10-2241-2013, 2013.

The UK House of Commons Science and Technology Select Committee has recently launched an inquiry entitled “Climate Change: public understanding and its policy implications”, which is due to address the issue of communicating climate change research. This inquiry was raised following a recent surge in climate change scepticism and a diminishing public concern regarding its effects, with a survey suggesting that 76% of people were concerned by climate change in 2009 against 81% in 2008.

Climate change is certainly a topical issue. It lies at the junction between a panel of physical scientific disciplines (atmospheric physics, oceanography, ecology, chemistry and computing) and social sciences, being a prominent topic in politics and policy-making. There seems to be a constant flow of climate-related articles in the media. They may describe the negative effects of climate change on our environment or the place of climate and environmental change within education, with recent talks to include climate change on the school curriculum in the US being but one recent example. But to what extent do people really take notice? What does the public actually think of climate change and do they really consider our environment to be at risk? As a climate scientist, this got me thinking: How can we better communicate scientific results and the overwhelming consensus within the research community that action needs to be taken?

The inquiry: What, who and how?

In their call for evidence, the Commons Select Committee has outlined a series of questions to be discussed at the inquiry:

• What is the state of public understanding and opinion on climate change issues? What is the role of publicly funded scientists, Government Departments, scientific advisers and the media in communicating climate change?
• Who does the public trust?
• How can public understanding be improved? How important is this understanding in developing appropriate policy?

So what does the public think about climate change?

In September 2012, scientists from the British Antarctic Survey, the Universities of Cambridge and Cardiff and the Global Sustainable Institute at Anglia Ruskin University published a report on public attitudes to climate science and how this science is represented in the media. The purpose of the report was to examine how climate change research is being communicated, the public’s attitude towards it and the means by which this communication could be improved. To go about answering these questions, the investigators carried out a series of focus groups across the UK population. In each case, participants were presented with a range of UK newspaper, radio and television articles on climate science and invited to pick one article for discussion. They were then asked to judge the chosen piece based on the level of interest in the subject, how easy it was to understand and where the news piece could be improved.

Tongue of a glacier on Baffin Island, Canada. Credit: Angsar Walk.

The study revealed that 80% of the survey participants did believe that the world’s climate is changing through a combination of both human activity and natural variability. However, many people felt that they were not properly informed about new findings in climate science and therefore felt relatively uninterested in the field. More importantly, nearly half of the surveyed people believed that scientists exaggerate the seriousness of climate change and trust in “authority groups” such as government, industry, environmental groups, scientists and the media has decreased in recent years.

Climate change and public opinion – who matters?

Despite this growing skepticism, a recent poll published by climate and environmental policy news fact-checker Carbon Brief revealed that the UK population trusts scientists more than any other source to inform them about climate change. In second position, the poll placed Green charities, closely followed by BBC journalists. Far behind and in last place came both politicians and social media, with only 7% of voters trusting these sources to provide accurate, up-to-date information. In addition, the poll showed that as many as 64% of participants did not trust politicians’ information and 53% would not trust the information they read in social media.

Despite trusting scientists most, the number of concerned citizens is still dwindling. So how can we as scientists better convey our results and our concern? The last issue of the journal Nature Climate Change dedicated an editorial to the “climate consensus” and the factors affecting public opinion. The article revealed that the public would be more likely to believe that human causes are affecting long-term climate change if there was a clear scientific consensus that anthropogenic global warming is indeed happening. Luckily, this consensus does exist among the vast majority of climate scientists, so where is this information lost in translation?

Could, may, possibly, maybe… The uncertainty paradox

While the vast majority of people trust scientists, the 2012 report’s working groups also revealed that uncertainty is a big issue for public trust, with readers getting frustrated at fuzzy and seemingly contradictory statements. What is the point of saying that something could possibly happen without developing on this statement? On what basis should people then make decisions? The difficulty is of course that natural variability of the climate system and the complexity of the physical mechanisms involved mean that climate predictions intrinsically have a degree of uncertainty associated with them. There is no real debate among the climate scientific community that we humans are influencing our climate and that this will have consequences on a number of different parameters and sub-systems.

Global warming predictions for the end of the 21st century from the Hadley Centre HadCM3 climate model. Source: Wikimedia Commons.

The question is what impact do these changes have in different parts of the world and to what degree can climate models assign a particular outcome to a specific human source? It is perhaps the definition of this uncertainty that scientists need to spend time explaining. Yes, a cluster of climate models may produce a range of results for a particular experiment. But ultimately they may all show the same trend or allow us to draw hard conclusions that can be translated to the public. When talking about climate forecasting at a recent Royal Meteorological Society meeting, Swedish Meteorologist Anders Persson stated that uncertainty is inevitable but must be acknowledged. He suggested that we stop blaming the models and start taking responsibility for uncertain forecasts. Uncertainty exists, full stop. Let’s start acknowledging it and, more importantly, explaining it.

So how can we scientists improve the communication of climate change research?

Given that scientists are in fact trusted and have a good understanding of the state of the art of climate research and the areas that still need exploring, it seems to me it is up to us to reach out to the public and talk about our research and its results. If, for each paper published in top scientific journals, the authors associated a short, simple piece of outreach to explain the steps taken to come to their conclusion and explain why they trust their results, perhaps more people would find an interest in climate research and would be willing to take personal action. But without this incentive and hard evidence clearly agreed upon by scientists, it is perhaps understandable that climate change is not the priority on everybody’s personal agenda. To put it in the words of financier Jeremy Grantham: “Be persuasive. Be brave. Be arrested (if necessary)”. In other words, let’s take risks and show our involvement and concern to make sure that it is heard by the public and policy-makers. This is possibly more easily achieved by established professors (and financiers such as Jeremy Grantham himself) than by young scientists trying to fight their way through to the next fellowship and piece of funding. But I believe the bottom line is true. Scientists must make a stand and show their agreement. Most of us are concerned and have the data to back this up, so let’s make it clear and give people a way to understand our work and ask their questions.

By Marion Ferrat, postdoctoral researcher at Imperial College London

This week at the EGU General Assembly, we’ve heard how the global environment is changing before our very eyes. As the Earth warms, sea levels rise, and weather patterns shift, the food security, health, and economic prosperity of societies around the world has come under threat. In the Anthropocene, an era dominated by human impact on the natural world, it seems that environmental and development goals are fast becoming one and the same. We have to find solutions that will allow us to live and grow sustainably, a task that falls largely to the hands and minds of the scientific community.

To shepherd Global Environmental Change (GEC) research into a new era of collaboration, communication and innovation needed to meet these challenges, the Future Earth initiative was conceived at the Rio+20 UN Summit on Sustainable Development last year. EGU’s GeoLog sat down with Anne-Sophie Stevance of the International Council for Science and Owen Gaffney, the Director of Communications for the International Geosphere-Biosphere Project, two of the driving forces behind this new project. Here, they explain what Future Earth means for geoscientists.

Future Earth hosted a Townhall Meeting at the EGU Assembly on Tuesday night to introduce their initiative and solicit feedback from the scientific community. Credit: Sue Voice.

First of all, what is Future Earth?

AS: Future Earth is a new international research program focused on producing the knowledge we need to address global environmental changes and the transition towards sustainability. The idea is to unite people who are not used to working together, building a community around Future Earth with stakeholders from academia but also other from sectors like policy and business. We are still very much in the early stages of development and we are eager to work with scientists on defining our research agenda and structure.

What sets Future Earth apart from previous Global Change initiatives?

OG: For the past 20-30 years, Global Environmental Change (GEC) research has focused on understanding human impacts on the planet and how the planet works. For Future Earth, that research agenda is changing to one centered on global sustainability. Also, the world has become far more interconnected in recent decades. Future Earth now has dual roles: to continue coordinating research but also to promote international collaboration and outreach.

How will Future Earth actually work from an operational point of view?

AS: Our goal is to have scientists come together with common research interests and populate the research framework from the bottom up. We don’t want to impose things from the top. Next week, for example, we will host a networking conference for young scientists to discuss food futures. It’s done within the framework of Future Earth and will be all about discussing the research agenda, identifying research themes and priorities, and developing collaborations.

You gave the example of food futures, but what are the other topics that fall under the purview of Future Earth?

OG: The starting point is our three broad research themes: dynamic planet, global development, and transformations toward sustainability. Within these, we’ve already had a call for proposals in two research action groups on freshwater and coastal vulnerability, and we are working on food security and infrastructure. But we want to be very open and create a platform that any scientist feels they can approach.

Owen, your expertise is in communication. Will communication be a big part of Future Earth?

OG: The old model of communication was to make more knowledge accessible to people. I think we need a new model that starts with this idea of co-design. This involves engaging the stakeholders from the beginning so that the users of this knowledge have a larger vested interest in the research and feel that it is addressing their needs.

AS: We highlight co-design as a big opportunity that can bring a lot of value to Future Earth but we also identify it as a challenge. We need to define research questions that appeal to policy and business and that requires building a common language.

Is that where data visualisation comes in? You spent a big part of the Townhall Meeting on Tuesday night talking about this.

OG: Data visualisation is rapidly evolving, and it is such a powerful way of communicating science. It can change how you think about the world by displaying scientific evidence in an understandable way and impressing issues of scale. One of the added values of Future Earth is that we can create partnerships with organisations like Google or Mozilla or Microsoft who are investing heavily in data visualisation. We also plan to offer summer schools on data visualisation and communication for young scientists. Bringing up a community who’s thinking like that is very important, and we need to given them the skills to interact with the public, the media, and policymakers in new ways.

You expressed interest in engaging funding agencies in the goals of Future Earth. Can you explain how that might work?

AS: We are already working with the Belmont Forum, a coalition of groups that fund environmental research, as well as NSF, NERC, national funding agencies and others. They have been involved from the start in setting up Future Earth and establishing the research agenda. Now, they can help further the goals of Future Earth by setting common criteria for funding – for example, that we want to see natural and social sciences together, we want to see elements of co-design and outreach to stakeholders. That incentivises the core elements of Future Earth.

OG: In a similar way, the International Polar Year (IPY) was an extremely positive model of how international endorsement can help with funding. It built a very large community very quickly and that community held together for a long time after the IPY was over. We can adapt some of their ideas for endorsing projects, which can then be taken to funding agencies with a stamp saying “these have been endorsed by Future Earth, will you fund it?”.

At the end of this 10-year initiative, what is an example of an outcome of Future Earth that you would consider a success?

AS: For me, it would be a young scientist trained in holistic, trans-disciplinary research and working on developing pathways to sustainability or researching the link between GEC and how we can transition to sustainability.

OG: The new UN sustainable development goals are going to start in 2015 and run to 2030, but it will be important for the research community to play a role in measuring, monitoring and evaluation the targets underneath the goals. To me, that would be a significant policy outcome from the Future Earth initiative.

You can learn more and get involved at http://www.icsu.org/future-earth.

Here is a powerful data visualisation by Owen Gaffney to inspire you more!

By Julia Rosen, Freelance science writer and PhD student in Earth, Ocean, and Atmospheric Sciences at Oregon State University

You’ve probably heard of supermodels like Heidi Klum and Kate Moss, but have you heard of SUMO? It’s an abbreviation for a project called Super Modeling by Combining Imperfect Models, and although it doesn’t sound nearly as glamorous, it may mean big things for climate modeling. This innovative approach, pioneered by an interdisciplinary group of scientists from around the world, seeks to build on the success achieved by using the mean of an ensemble of different climate models to predict future climate change. Instead of running the models independently and averaging them after the fact, SUMO has developed a framework to couple models interactively during a simulation. This might not seem like a big change, but it represents a tremendous technical challenge, one that might prove well worth the effort if the project achieves its ambitious aims. So far, the results look promising.

This figure from the Intergovernmental Panel on Climate Change 4th Assessment Report released in 2007 shows predicted changes in regional precipitation patterns associated with climate change using the mean of an ensemble of state of the art climate models. Source: IPCC.

To estimate the effects of anthropogenic climate change, researchers use complex mathematical models to simulate the behavior of the Earth’s climate system. These models are based on a handful of fundamental physics equations – like conservation of momentum, energy, and mass – and they overwhelmingly agree on the general direction of changes we can expect to see (for example, they unanimously project that global average temperature will rise). However, individual models produce markedly different estimates of the amplitude of future warming, the regional pattern of precipitation changes, and the sensitivity of global temperature to atmospheric CO₂ concentrations. These discrepancies arise from differences in model architecture and most importantly, from the ways each model accounts for processes that cannot be simulated organically in the model because they operate on scales too small to be captured, or because they require additional physics.

State of the art models disagree about the magnitude of future warming. The colored lines represent different emissions scenarios while the grey error bars on the right show the spread between models. Source: IPCC.

Researchers have long noted that the best way to synthesise these disparate results is to take the average of a group of climate models. This approach generally provides the best match to empirical observations, and the spread between models provides a useful measure of model uncertainty. While the success of averaging might seem lucky, or even coincidental, many scientists say it isn’t all that surprising. After all, people don’t pick values for important model coefficients out of thin air; they spend a great deal of time trying to choose optimal numbers by “training” the models on observational data and by using outside constraints for the most likely value of a parameter. “It’s like one of those games at the fair where you have to guess the number of balls in a jar,” says Dr. Win Wiegerinck, a machine learning specialist at Radboud University Nijmegen in Holland who presented early results of the SUMO project at the EGU General Assembly on Monday. “If you take the average of many people’s guesses, you often get the right answer.”

Based on this idea, Wiegerinck and his colleagues at the SUMO project are taking averaging to the next level. At every time step of a multi-model simulation, they require the models to agree on an intermediate result, essentially binding every model to the instantaneous mean. “If conventional model-mean studies use a coupling of zero,” says Wiegerinck to put things in sufficiently quantitative parlance for the EGU crowd, “SUMO represents setting the coupling between models to infinity.” He notes that it is possible to use any degree of coupling between these two extremes and in their initial experiments, the SUMO group has experimented with partially and fully coupled model ensembles. The benefit of this new approach is that it might prevent models from diverging dramatically due to cumulative errors that would grow during independent model runs. Their hope is that it will also provide the best way of simulating reality.

The Lorenz Attractor is a set of differential equations that illustrates the so-called “butterfly effect” in which the occurrence of a significant event (like a hurricane) might depend on whether or not something seemingly inconsequential happened before (like a buttefly flapping its wings). The solution of the Lorenz Attractor depends strongly on the initial values and, coincidentally, looks a bit like a butterfly itself. Source: Wikimedia Commons.

SUMO brings together experts in climate science, nonlinear dynamical systems, and machine learning, like Wiegerinck, to tackle the considerable challenge of coupling many complex models. As a preliminary test, they modeled a simple chaotic system like the famous Lorenz attractor. It seemed like a good prologue to climate modeling, because like the global climate system, the Lorenz equations depend strongly on small differences in initial conditions that can lead to drastically different solutions. After passing this test, SUMO embarked on an experiment with a simplified atmospheric circulation model.

In this first attempt, the coupled and ensemble-mean models performed better than any individual model at simulating northern hemisphere circulation, as expected. In addition, SUMO performed as well as the traditional model-mean approach in simulating the average climate state, a sign that the researchers are on the right track. The coupled models also did a bit better than the ensemble mean at simulating the correct degree of variability, an achievement just as important as getting the absolute value correct in a climate model. These results are encouraging, although the scientists stress that it is too early to know whether or not SUMO will be up to the long-term goal of predicting climate using complex models like the ones employed by the Intergovernmental Panel of Climate Change Assessment Reports to advise policymakers around the world on the expected impacts of climate change.

The researchers are nonetheless optimistic about short-range predictions. Dr. Frank Selten of the Royal Netherlands Meteorological Institute who oversees the climate science branch of SUMO thinks coupled models could be very useful for sub-annual forecasts. He says they have the potential “to reduce the contribution of model error to the prediction error [and] to estimate the reliability of the forecast.” In any case, SUMO represents a novel approach to climate modeling, and one to keep an eye on as it progresses towards integrating increasingly complex models. Based on the solid first results shown here at EGU, it looks like SUMO may indeed have something in common with those other supermodels: it might just be onto the next big trend.

Source: Wikimedia Commons

By Julia Rosen, Freelance science writer and PhD student in Earth, Ocean, and Atmospheric Sciences at Oregon State University

The Lena River flows throughout Russia from its source in the Baikal Mountains out into the Arctic Ocean, where the delta’s landscape is dominated by ice-rich Yedoma and thermokarst lakes. Thermokarst lakes have been identified as a source of carbon release to the atmosphere and Yedoma-like lake sediments are known to release more methane than any other sediment due to their incredibly high carbon content. So what is a thermokarst lake?

The Lena River Delta, dominated by Yedoma uplands and thermokarst lakes. Image taken by LANDSAT (source: NASA).

Thermokarst is a landscape that results from the thawing of both icy permafrost and larger ice masses. In northern Siberia, thermokarst starts to develop at the surface: once the ground subsidises, water accumulates in a series of small basins known as alasses. They continue to grow in size to form thermokarst lakes, which can either drain or coalesce with neighbouring lakes to form even larger ones that can reach several kilometres in diameter. When thermokarst lakes drain, they leave behind much smaller lake remnants that lie with a flat basin with steeply sloping sides. Multiple cycles of thermokarst development can occur within a single thermokarst basin to create a complex thermokarst landscape peppered with lakes and islands.

Kurungnakh Island, which lies within the Lena River Delta, formed during the Pleistocene and is part of the region’s thermokarst landscape. The cliff below exposes the Yedoma, a series of silty permafrost deposits with high ice and carbon contents. Permafrost is soil that is either at or below the freezing point of water and forms in regions where the mean annual temperature is below this. Permafrost soils are very rich in carbon, which is stored as peat and methane. The release of this carbon into the atmosphere has the potential to accelerate climate warming through a positive feedback system. That is, where a small change (the release of methane due to permafrost melt) has the capacity to cause a change of even greater magnitude (the presence of more methane in the atmosphere increases the temperature and accelerates the rate of permafrost degradation, releasing even more methane…).

The most immediately recognisable form of permafrost degradation is the presence of thermokarst – you can get a feel for this in the photo below:

“Kurungnakh Island” by Sebastian Zubrzycki. Distributed by the EGU under a Creative Commons licence.

The pale lower unit is comprised of fluvial sand, overlain by ice-rich permafrost (light grey) and capped with a thin covering of Holocene peat. Fluvial sands in this region are relatively ice-poor, which limits the capacity for further thermokarst development. While there is relatively little capacity for further thermokarst development, it is important to consider other processes associated with permafrost degradation and the rates at which they occur. In doing so, we can better quantify future carbon fluxes from permafrost soils in as the climate warms.

Reference:

Morgenstern, A., Grosse, G., Günther, F., Fedorova, I., and Schirrmeister, L.: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta, The Cryosphere, 5, 849-867, doi:10.5194/tc-5-849-2011

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

Ocean thermal expansion, that is, the increase in water volume due to temperature alone, is relatively well understood – as is the retreat of both mountain glaciers and ice caps. While most models simulate these effectively, there is little understanding of how both the Greenland and Antarctic ice sheets will respond to climate change. This is because the full extent of ice-ocean interactions is not included in climate models – it’s no wonder when there are so many factors to consider: melting of mountain glaciers, ice caps and polar ice sheets, glacial isostatic adjustment and ocean thermal expansion to name just a few!

Mahé Perrette and his colleagues have developed a novel approach for sussing out sea level rise (SLR); combining simple models with general circulation models (GCMs) to use the benefits of both in predicting future change. To get an idea of the uncertainties associated with SLR, take a look at this graph, in which red is a highly uncertain prediction (up to 70 cm variation) and dark blue is an estimate we can be quite confident of (only 5 cm variation):

The first of the three panels combines the uncertainty for all components of SLR considered by Dr Perrette and his team – there’s really not much blue there is there?! [Source: Perrette et al., 2013].

Both the magnitude of SLR and the timescales over which it occurs varies wildly between models, but it remains clear that the effects of SLR will be felt most in the low-lying coastal regions of the world: from small island nations such as Tuvalu, which at only marginally above sea level, is a country only too aware of this threat; to the densely populated, and agriculturally important, coastal plains of Bangladesh.

Each of the contributions to SLR (meltwater from the Antarctic and Greenland Ice Sheets, and melting of mountain glaciers and icecaps) vary locally, which means that SLR will also vary from region to region. This interactive map by Perrette and his team is a great demonstration of how SLR varies throughout the world under different emissions scenarios.

Predicted sea level rise for coastal regions. The key indicates the different components contributing to SLR: MGIC = Mountain Glaciers and Ice Caps, AIS = Antarctic Ice Sheet, GIS = Greenland Ice Sheet and GIA = Glacial Isostatic Adjustment [Source: Perrette et al., 2013].

Rates of relative sea-level change [Souce: Riva et al., 2010].

Gravitational forces influence global, as well as local, water distribution. The declining mass of ice caps at the poles means there will be weaker gravitational forces acting on Arctic and Antarctic waters. The weakening of these poleward-pulling forces will cause water to be redistributed throughout the globe, resulting in greater SLR at the equator than at the poles. So, despite the large local variations in SLR, its effects will be felt most in the tropics and at the equator.

By Sara Mynott

References:

Perrette, M., Landerer, F., Riva, R., Frieler, K., and Meinshausen, M. (2013), A scaling approach to project regional sea level rise and its uncertainties, Earth Syst. Dynam., 4, 11-29, doi:10.5194/esd-4-11-2013.

Riva, R. E. M., J. L. Bamber, D. A. Lavallée, and B. Wouters (2010), Sea-level fingerprint of continental water and ice mass change from GRACE, Geophys. Res. Lett., 37, L19605, doi:10.1029/2010GL044770.

In this month’s Geoscience’s column, Alex Stubbings discusses the water scarcity problems in the Middle East and North Africa region and  the recent developments in modelling water resources here. 

The Middle East and North Africa (MENA) region is considered the most water-scarce region in the world. As such, the region faces a multitude of challenges in the 21^st century including population growth, economic development, food production and climate change. With these challenges in mind, a team of researchers led by hydrologist Dr. Peter Droogers explored how “Water resources trends in the Middle East and North Africa towards 2050” will change over the first half of the 21^st century. The study is published in EGU’s Open Access journal Hydrology and Earth System Sciences.

Presently, there exist huge spatial variations in water allocation, and the region as a whole is the driest and most water scarce region in the world. This is increasingly affecting the social and economic development of the region.  For example, the average water resource availability per capita is only marginally above the physical water availability of 1076 m³yr^-1, compared to the world average of 8500 m³yr^-1.

The prevailing arid conditions found within the area mean that over 85% of the MENA region can be considered desert. It follows that the region can be further subdivided into three distinct climate spaces: the Maghreb region, which constitutes North African countries with a Mediterranean climate, and is climatically heterogeneous; the Gulf Cooperation Countries located within the Middle East, and have a typical desert climate; and lastly, the Mashreq region, which includes countries that have a milder and wetter climate, such as Iraq and Syria.

The Middle East and North Africa (MENA) region (blue), (Source: Wikimedia Commons).

Therefore the lead question Droogers et al. focused on filling vital knowledge gaps. Indeed, they highlight that “a complete analysis on water demand and water shortage over the coming 50 year period based on a combined use of hydrological and water resource models, remote sensing and socio-economic changes has never been undertaken for the MENA region”. Moreover, they intend to achieve this by assessing water demand in the 22 MENA countries by taking into account the dynamics and uncertainties of climate change, demographic changes and economic development.

The team used two distinct models that covered a 50 year time period (2000–2050). Firstly, the PCR-GLOBWB (PC Raster Global Water Balance) hydrological model was run to determine the internal and external renewable water resources for present and future climate. And the second model employed was a water allocation model, referred to as the MENA Water Outlook Framework (MENA-WOF). This was chosen to analyse the linkage between renewable water resources and sectoral water demands, and utilises the Water Evaluation and Planning (WEAP) framework.

This approach allowed the research team to simulate the average hydrological conditions with great accuracy – best demonstrated by its ability to accurately model and replicate actual flows on the Blue Nile, White Nile and Atbora tributaries. The team singled this out as a key indicator of its robustness. They noted that other similar studies, to date, have yet to model these flow regimes accurately.

Long-term average annual observed and simulated flow (Source: Droogers et al., 2012).

Nevertheless, as with other empirical modelling studies the authors issue a caveat: that the results regarding water resources, derived through GCM output, should be interpreted with great care. The model predicts total water shortage will increase by 157 km³yr^-1, while water supply and demand are only projected to increase by 132 km³yr^-1.  In short, the overall trend is that all MENA region countries will see an increase in water shortages, as the increase in supply will not meet the growth in demand, except for Djibouti.

Droogers et al. naturally consider the contribution of climate change to water scarcity. Their results indicate that only 10% of the change in water demand will be attributed to climate change and the rest entirely due to socio-economic changes (under their average climate change scenario). Furthermore in the other two scenarios, wet and dry, socio-economic factors, again, are more important than the effects of climate change. However, they emphasise that despite the small contribution made by climate change its effects should still be taken into consideration when planning adaptation interventions.

The contribution of socio-economic changes and climate changes on total water demand in 2050 (Source: Droogers et al., 2012).

The findings presented here by Droogers et al. are unique. They have combined different data, models and tools in order to forecast changes in water demand and supply over a geographically diverse area. Despite this novel approach, a clear drawback of the study, recognised by the team, is that the spatial resolution is lower than the output for smaller geographical areas and utilising a single methodological approach would have allowed more in depth comparisons to be made between countries.

When looking at the wider landscape of climate change impacts and adaptation strategies the team refer to a World Bank study from 2010, which estimated the cost of adaptation for developing counties at 0.12% of GDP, with costs associated with adaptation increasing linearly with time. The authors offer a number of pragmatic solutions, which fall under the umbrella of ecological modernisation, highlighting the potential of desalination plants.

As a work in progress, Droogers and his team offer direction for future work. Firstly, they suggest that further research should be carried out at a higher spatial resolution, for instance, employing the same methodology but focusing on individual countries rather than on an entire region. And secondly, of the need to analyse potential adaptation strategies and the associated costs of implementing them within the region. Both directions have their merits, but with the uncertain nature of climate change makes it difficult to distinguish which step we should take next.

By Alex Stubbings

This week’s Imaggeo on Mondays is brought to you by the photographer herself, Marion Bisiaux (now at Stendhal University, Grenoble, France), who tells us about her exciting field trip to the British Columbia’s Coast Range.

“Combatant Col under a storm” by Marion Bisiaux, distributed by the European Geosciences Union under a Creative Commons licence.

This picture was taken during the Waddington Range Ice Core Project in which I participated during my PhD at the University of Nevada, Reno, US and at the Desert Research Institute, also in Reno. The scene was captured in July 2010, during a month-long field trip at the Combatant Col, the mountain pass below Mount Waddington in British Columbia’s Coast Range that sits at 3000m elevation and contains more than 200m of ice. The aim of the project was to drill an ice core to retrieve information on the past climate of the area. The results were published in 2012 in the Journal of Glaciology and are available online.

The camp (tents only) was located just below the massive north face of Mount Waddington. The weather was rather rough as we had several storms hitting the camp, but the scenery was impressive, with avalanches running on Mount Waddington’s face, crevasses, overhanging seracs, among other phenomena. The photograph shows the high winds on the Mount that stopped the ice-core drilling for a few days and forced drillers to hide in their tents.

Notwithstanding the strong weather and striking scenery, what I remember the most is the human aspect of this scientific expedition. Everyone was very motivated, working very hard to make the drill happen, and united by the same goal: the success of the expedition and the increase of knowledge.

This field trip will be the topic of a book Carnet Glacé (in French), which will tell the story of the expedition.

By Marion Bisiaux, glaciologist and science communication student

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Melting ice” by Thomas Ernsdorf, distributed by the European Geosciences Union under a Creative Commons licence.

The speed and extent of Greenland’s ice sheet melt dominated the media over the summer, and for good reason. Dramatic satellite images showed that, in just a few days, 97% of the island’s ice sheet surface thawed, melting over a larger area than at any time in more than 30 years of satellite observations. Usually, during the summer only around half of the surface of Greenland’s ice sheet melts and much of it refreezes or is replaced.

The Steenstrup Gletscher (Glacier) is a wide glacier in northwestern Greenland, known for the number and size of the icebergs that are calved from its spectacular central portion. Steenstrup has retreated 10km over the past 60 years and around 20km over the past century, a worrying trend because of the potentially catastrophic consequences of rising sea levels on coastal areas worldwide.

Meteorologist Thomas Ernsdorf (University of Trier, Germany) describes his encounter with this massive wall of ice, when he captured this spectacular picture, “I took this shot during Greenland’s melting season. The picture shows melting ice in front of Steenstrup Glacier in June 2010. It was taken at a height of 30m above ground level using the Polar 5 aircraft. I was there as part of the IKAPOS campaign, which aims to investigate the North Water (NOW) polynya, a huge area of open water surrounded by sea-ice.  As a consequence of global warming, the ice mass of Greenland will be reduced enormously.”

The Polar 5 aircraft, a Basler BT-67 featuring specialised aeronautical and scientific instrumentation, is operated by the Alfred Wegener Institute for Polar and Marine Research and is widely used to measure the extent of the Arctic ice melt. It was inaugurated in October 2007. A photo gallery featuring this specially equipped plane can be found on the Alfred Wegener Institute website.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.

“Ellesmere Island” by Jean-Daniel Champagnac, distributed by the European Geosciences Union under a Creative Commons licence.

Located within the Canadian Arctic Archipelago, Ellesmere Island is the world’s tenth largest island and features Canada’s most northerly point but little else apart from vast landscapes of pristine natural habitat. It is separated from Greenland only by the Nares Strait, a major pathway for sea ice flushing out of the High Arctic.

Belonging to the Canadian territory of Nunavut, Ellesmere’s permanent population is under 200, most of whom endure the hostile weather found at Grise Ford, where the annual temperature is a staggering -16.5°C.

It comes as no surprise, then, that this mosaic of colours was captured from high above Ellesmere’s unforgiving environment. Jean-Daniel Champagnac, of the Geological Institute of the Swiss Federal Institute of Technology, Zurich, explains, “This picture was taken through the window of an airplane cruising at around 10,000m en route between Frankfurt, Germany and Anchorage, Alaska. Here you can see the bare rock of Ellesmere Island, with presumably folded sedimentary rocks, and a frozen fjord being unglaciated. This picture, taken in June 2011, has been quite substantially modified from the raw initial picture.”

As with many untouched Arctic environments, it is thought Ellesmere may be rich in natural resources, specifically in thermal coal deposits used to produce heat and electricity. If confirmed, this finding could be pivotal for the future of Nunavut. Canada’s mostly-aboriginal territory (83.6% Inuit, according to the 2006 census) is currently experiencing an energy crisis.

About his picture, Champagnac concludes, “It is always worth having a camera along when you fly, especially on a clear day.” We couldn’t agree more and we encourage you to submit more of your aerial shots to Imaggeo.net.

Imaggeo is the online open access geosciences image repository of the European Geosciences Union. Every geoscientist who is an amateur photographer (but also other people) can submit their images to this repository. Being open access, it can be used by scientists for their presentations or publications as well as by the press. If you submit your images to imaggeo, you retain full rights of use, since they are licenced and distributed by EGU under a Creative Commons licence.